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By M. Hamarat

Freeport-McMoRan Copper & Gold (FCX) is committed to preserving and enhancing biodiversity in the areas in which we operate. As a member of the ICMM, FCX is committed to implement the 10 Sustainable Development (SD) Principles throughout our business. FCX is also a member of the Wildlife Habitat Council (WHC), a nonprofit coalition dedicated to protecting and enhancing wildl ife habitat. In alignment with ICMM SD Principle 7 and our Environmental Policy, FCX has set a performance goal to prepare a biodiversity inventory in 2010 and land management plan by end of 2011 for all active mining sites. In 2010 FCX established a Biodiversity Task Force to assist sites in biodiversity management; optimize use of resources around the globe; implement FCX goals and targets; and align biodiversity programs with ICMM principles and guidance. The task force consists of Environment and SD Department management, scientists and engineers from FCX sites, and WHC staff. The Task Force recently issued a biodiversity inventory guidance document to set expectations and provide consistency across the sites when developing a biodiversity inventory and land management plan.

Jan 1, 2011

By J. Kretschmann, N. M. Smith, J. F. Brune, P. Goerke-Mallet

Coal production and coal use for electric power generation are diminishing worldwide. Germany will phase out lignite mining as well as lignite and hard coal-powered electricity generation by 2038. In the United States, coal production has dropped by more than 50% since 2006, including in key coal production states like West Virginia and Wyoming (EIA 2021). Closing mines and power plants across entire mining regions has significant socio-economic impacts. Existing industries must be focused on the post-mining economy by attracting new industries, and implementing job retraining programs for displaced workers, as former mining regions transition towards agricultural, industrial and recreational use. This paper examines the German “exit from coal” under the 17 UN Sustainability Goals and illustrates the complex procedures, interrelationships, risks, and rewards of the transition towards renewable energy sources, including wind, solar, hydrogen, and bioresources.

Mar 2, 2022

By Richard D. Lang

Introduction Argyle is located in the Kimberley region in northwest Australia (Fig. 1). It is a significant diamond discovery by world standards and is the first major diamond find in Australia. The deposit consists of a pipe and associated alluvial deposits. Before the 1970s, diamonds were known to exist only sporadically in Australia. They have been found occasionally in association with gold deposits in Western Australia. There is a small deposit near Copeton in New South Wales. Some alluvial occurrences have also been found in Victoria, South Australia, and New South Wales. The first indicator minerals in the Kimberley region of Western Australia were discovered in January 1973. Production from the alluvial deposits at Argyle began in 1983. A $430-million construction program to develop a mine and treatment plant capable of producing 25 million carats per year was completed in December (1 carat = 0.2 grams). Ownership and management Participants in the project are known as the Argyle Diamond Mines Joint Venture. The group consists of CRA Ltd., 56.8%; Ashton Mining Ltd., 38.2%; and the Western Australian Diamond Trust (formerly Northern Mining Corp.), 5%. The project is managed by Argyle Diamond Mines Pty. Ltd., a wholly-owned subsidiary of CRA. Marketing is undertaken separately by the Western Australian Diamond Trust and by Argyle Diamond Sales Ltd. (for CRA and Ashton Mining groups). History Ownership of the Exploration Joint Venture has changed over the last 12 years as various parties changed their shareholdings. The original Kalumburu Joint Venture was formed in 1972 with five participants, each holding a 20% interest. By 1983, a number of ownership changes had occurred. The end result is that two original participants have sold out. CRA now holds a 56.8% share and the Ashton Mining Group holds 38.2%. CRA also assumed project management in January 1977. Table 1 demonstrates the long lead times involved in developing a project.

Jan 1, 1986

By S. Ilyas

Technical innovation in electrical and electronic equipment with new functions and design, stimulate consumer?s purchasing desire towards the latest equipments and this leads the rapid increase in the production of increased amount of waste materials Treason et al (2006) have reviewed the data on electronic waste generation in different parts of the world. Studies by Bertram et al (2002) have also affirmed that waste electrical and electronic components are the fastest growing waste category; this emphasizes the need for efficient recycling strategies. Recycling of electronic waste is an important subject not only from the point of waste treatment but also from the recovery aspect of valuable materials. However, recycling of electronic scrap is still quite limited due to the heterogeneity of the materials present in the products (Veit et al. 2005). A bioleaching based process offers a number of advantages compared to the conventional pyro or hydrometallurgical methods (Lee et al. 2007; Lee and Pandey, 2012). The advantages include simple, inexpensive (in some cases) and eco-friendly approach besides, generation of less active leach residue then other metallurgical processes. Though, biohydrometallurgical process has been successfully applied for the leaching of metals from ores (Olson et al. 2003; Rawling 2000), data pertaining to its application for the extraction of electronic scrap is still scanty. Recently, a few studies have been undertaken for extraction of metals from electronic scrap/printed circuit boards (Brandl et al. 2001; Faramarzi et al. 2004; Choi et al. 2004, Ilyas et al. 2007; Ilyas et al. 2010). These studies were conducted with mesophilic chemolithotrophic (Acidithiobacillus ferooxidans and Acidithiobacillus thiooxidans) or cyanogenic bacteria (Chromobacterium violaceum) or moderate thermophilic bacteria (Sulfobacillus thermosulfidooxidans). However, compared to bacterial leaching, fungal leaching has the following advantages: (i) ability to grow under higher pH, and thus is more suitable in bioleaching of alkaline solid waste (ii) a generally faster leaching process with shorter lag phase (iii) Chelation of excreted metabolites (e.g. organic acids) with metal ion, thus reduce its toxicity to the biomass (Burgstaller et al. 1993; Aung and Ting 2005). The specific objective of this work was to; ? Collection, isolation and enrichment of fungal strain ? Evaluate the abilities of Penicillium chrysogenum to leach metals from electronic scrap at various leaching modes (one-step bioleaching, two-step bioleaching, spent medium leaching, fresh medium leaching, leaching with deionised water and chemical leaching). ? Comparative study of all leaching modes

Feb 27, 2013

By M. M. Rajkovich

Just prior to the close of the century, the Federal Mine Safety and Health Review Commission issued its long-awaited decision in Berwind Natural Resources, et al v. Secretary of Labor, to usher in the new millennium. The case arose as a result of a mine explosion in Eastern Kentucky resulting in MSHA’s issuance of 225 citations, not only to the contractor, but to four affiliated entities of Berwind Corporation. While an Administrative Law Judge dismissed those citations as to three of the Berwind entities, both MSHA and the remaining Berwind entity appealed the case to the Commission. Although the Commission effectively left intact the Administrative Law Judge’s decision, it announced a new theory of liability that would apparently be applied in the future, namely the Unitary Operator Theory. This presentation will provide an in-depth look into the Berwind decision and explore the means under which MSHA might impose liability for contractor violations upon other entities in the future.

Jan 1, 2001

By D. J. Dodds, W. L. Schroeder

INTRODUCTION The plate loading test is a simple, useful tool in rock mechanics. The test consists of applying load to a rock surface and noting the resulting deflections. Plate loading tests are typically used to obtain modulus of deformation and related material properties, but can also provide information on blast damage and in situ stresses (1). Properties obtained are of course dependent on test procedure and test environment . In order to eliminate extraneous results it is essential that the interrelationship between the physical test environment and various rock properties obtained be thoroughly understood. Test interpretation is based upon elasticity methods, and the general assumptions made during analysis which include the following: 1. The rock is homogeneous, isotropic, elastic and continuous. 2. The stress is induced in a semi-infinite solid. 3. The plate is perfectly rigid or completely flexible. 4. Rock properties are independent of in situ stresses. 5. The plate and rock surface are smooth and parallel.

Jan 1, 1974

By Narendra N. Khatri, Michael Deutscher, Jozef F. Zurawski

Five sewer connections were required to divert Combined Sewer Overflow (CSO)from existing outfalls to an old underutilized large diameter brick sewer (the Easterly Interceptor). The connections were part of an on-going CSO control program by the Northeast Ohio Regional Sewer District (NEORSD) in the City of Cleveland, Ohio. Each connection was made by pipejacking and hand-mining a fiberglass-reinforced polymer (FRP) pipe through soft glaciolacustrine clays and silts. Jet grouting was utilized to stabilize the soils and fill the voids surrounding the interceptor prior to making the underground connection. Reinforced concrete liners were constructed inside the aging brick sewer to provide structural stability during ground improvements and connection work. The project also involved micro tunneling two approximately400 foot lengths of FRP pipe through soft ground using a slurry pressure balanced machine.

Jan 1, 2005

By Barbara C. Schickner

The long-awaited COSMAR study prepared under the auspices of the National Academy of Science reaches one emphatic conclusion that has been enthusiastically seconded by the mining industry: The 1977 federal surface mining act is "poorly suited" as a vehicle to regulate noncoal mining. Though the industry greeted the report with approval, the weight it will carry and the extent of its impact are yet to be felt. The COSMAR report makes no recommendations-that's a job left to the Administration's Council on Environmental Quality-and the prospect of legislation still hovers. For a closer look at the study, MINING ENGINEERING talked to COSMAR committee chairman James Boyd, a well-known presence in the mining arena for over 50 years. After highlighting some of the study's major points, Dr. Boyd comments on the report's impact and possible repercussions. Dr. Boyd, for those readers who haven't seen the COSMAR report, would you summarize some of its major findings? The committee analyzed the surface mining act to determine if it was applicable to noncoal mining and found that there were provisions of the act that either could not be met by existing technology or would be extremely difficult and not necessarily beneficial to adapt. We found that most noncoal mineral mines, despite their obvious diversity, can be considered in two major groups: 93% of all mines move 45% of all materials mined (mostly small units mining construction materials); and the few gigantic regional operations (2%)-copper, iron, phosphate, and uranium mines-that move 50% of the material. With few exceptions, neither of the two groups is amenable to the coal mining practices addressed by the act. The strip mine law was designed for coal mining, where land is regraded, revegetated, and returned to usefulness. In contrast, construction mineral quarries supply local needs for decades, remove most of the material from the immediate vicinity, and cannot be returned to their premining uses (though they have innumerable other valuable uses). The nation's huge mineral deposits require enormous capital investments, are vital to the nation's economy, and can take centuries to exploit. Any attempt to return these locations to premining use would be illogical. Pebble phosphate in Florida and red-bed copper in Oklahoma come near to meeting the conditions contemplated in the act. In addition to COSMAR's basic finding, the study also makes the following points: •Mining uses a relatively small part of the land resource, in contrast to

Jan 4, 1980

By Li Zhou

The kinetics of the dissolution of galena was studied by monitoring the mixed potential of a galena electrode in ferric sulfate solutions. The results show that the mixed potential of the galena electrode fluctuated with time in a regular pattern in a 0.1 mol/L Fe2(SO4)3 solution of pH 1.66 and in a 0.01 mol/L Fe2(SO4)3 solution of pH 2.33 at 35°C. The periodic accumulation and precipitation of lead ions at the galena electrode surface and the cyclical variation in pH at the galena electrode surface caused the oscillation phenomena.

Jan 1, 2008

By J. B. Gwiazda

Introduction Thick seams constitute a considerable portion of Polish coal reserves. In producing mines and those under construction, the reserves where the height is more than 4.5 m (15 ft) total about 24% of all the hard coal reserves. The reserves that are under urban and industrial areas can be extracted using stowing methods for surface protection. About 50% of thick seam reserves can be extracted by caving methods. Thick seam mining methods Thick seams are usually extracted by multilift methods. There are some methods of thick seam mining that generally can be divided into caving and stowing methods. The stowing method is more expensive, but must be used when mining to protect surface features. The more known methods of thick seam mining include • extraction of thick seam in ascending order with stowing ; • thick seam mining in descending order with consolidated stowing; • thick seam mining with gob consolidation; • thick seam mining in descending order with roof caving ; • sublevel caving thick seam mining system; and • thick seam mining system using an artificial roof. Thick seam mining with introduction of an artificial roof The most advantageous method of thick seam mining is the method using an artificial roof. The artificial roof usually consists of wire mesh. Such wire mesh must be durable and must prevent small rock fragments from passing through. The mesh is usually made of steel properly protected against corrosion. The artificial roof is placed on the coal floor of the top slice (Fig. 1). Caving rock falls on the artificial roof and is thus separated from the coal. The next slice is extracted under the artificial roof. The producing face of the next slice must progress within 10 m (33 ft) behind the front of the first slice. As the second producing face progresses, the wire mesh moves down on the coal floor and may be used as an artificial roof for the next slice. Thus, one artificial roof allows the extraction of several consecutive slices. Application of the artificial roof allows for clean extraction and reduces coal losses. It also eliminates the hazard of spontaneous combustion. Introduction of the artificial roof has been limited due to a lack of artificial roof laying equipment. Manual laying of wire mesh is a labor-intensive operation, and it delays face progress, resulting in poor productivity. To eliminate these problems, artificial roof laying equipment was designed at the Polish Central Mining Institute. The support and the method of laying operation is covered by a patent. Artificial roof laying powered support To extract thick seams using an artificial roof, four-leg shield supports with lemniscate linkage were developed (Fig. 2). This shield is used in the first top

Jan 3, 1987

By Barton J. Suchomel

Introduction Despite perennial economic turbulence, Argentina continues to push ahead with efforts to develop its fledgling hardrock mining industry. The country lacks the infrastructure and mining history of neighboring Chile, but contains vast areas of great resource potential. The eastern slope of the Andean Cordillera in west-northwest Argentina is a relatively little-explored region offering geology highly conducive to the occurrence of base and precious metals deposits. Past exploration has concentrated on locating and evaluating porphyry copper-molybdenum (Cu-Mo) type occurrences. Comparatively little attention has been given to precious metals potential. An interesting and important group of base and precious metals prospects in northwestern Argentina occurs within and adjacent to the Upper Miocene Farallon Negro volcanic complex in Catamarca province. The volcanic complex contains numerous base and precious metals vein occurrences, high gold porphyry copper prospects, and possible disseminated gold targets that have attracted relatively minor attention in the past. Various geologic aspects of the region have been reported by several workers (Llambias, 1970, 1972; Caelles et al, 1971; and Sillitoe, 1973). Regional geology The Farallon Negro volcanic complex is located within the Sierras Pampeanas morphostructural province about 200 km (125 miles) east of the main Andean Cordillera (Fig. 1). The Sierras Pampeanas is characterized by north-south-trending basin and range topography that developed during the Miocene and Pliocene. Uplifted blocks are composed mainly of lower Paleozoic metasediments and granitoid plutonic rocks unconformably overlain by Tertiary redbeds and minor carbonates. A consistent landward migration of volcanic and intrusive ac¬tivity occurred in this region of the Andes from the early Mesozoic through the mid-Tertiary. An eastward extension of magmatism during the Miocene and Pliocene resulted in the formation of the Farallon Negro volcanic center. Volcanism at Farallon Negro ini-

Jan 8, 1988

By B. Anameric, S. Kawatra

Pig iron nuggets, which have similar chemical and physical properties with blast furnace pig iron, were produced by a single step heat treatment of self reducing – fluxing dried greenballs. During this single step heat treatment the transformation of self reducing fluxing dried greenballs into pig iron nuggets did not take place instantaneously. Rather, it was composed of three transformation stages, (1) transformation of self reducing – fluxing dried greenballs into direct reduced iron (DRI), (2) transformation of DRI into transition direct reduced iron (TDRI), and (3) transformation of TDRI into pig iron nuggets. Thus, the objective of this research was to investigate these transformation mechanisms by analyzing the transformation stage products. The transformation stage products were produced at a constant furnace temperature of 1425°C and various furnace residence times. They were characterized according to their microstructure, microhardness and apparent density. The changes in the product’s physical and chemical properties with furnace residence time were utilized in understanding the transformation behavior, the chemical events that took place and the controlling mechanisms. It was determined that the transformations were dictated by the changes in the slag viscosity and wetting properties, and by carbon diffusion into metallized areas.

Jan 1, 2007

By M. K. Mohanty

One of the main objectives of this study was to evaluate a fine-coal cleaning circuit using an enhanced gravity separator specifically for a high sulfur coal application. The evaluation not only included testing of individual unit operations used for fine-coal classification, cleaning and dewatering, but also included testing of the complete circuit simultaneously. At a scale of nearly 2 t/h, two alternative circuits were evaluated to clean a minus 0.6-mm coal stream utilizing a 150-mm-diameter classifying cyclone, a linear screen having a projected surface area of 0.5 m2, an enhanced gravity separator having a bowl diameter of 250 mm and a screen-bowl centrifuge having a bowl diameter of 500 mm. The cleaning and dewatering components of both circuits were the same; however, one circuit used a classifying cyclone whereas the other used a linear screen as the classification device. An industrial size coal spiral was used to clean the 2- x 0.6-mm coal size fraction for each circuit to estimate the performance of a complete fine-coal circuit cleaning a minus 2-mm particle size coal stream. The ?linear screen + enhanced gravity separator + screen-bowl circuit? provided superior sulfur and ash-cleaning performance to the alternative circuit that used a classifying cyclone in place of the linear screen. Based on these test data, it was estimated that the use of the recommended circuit to treat 50 t/h of minus 2-mm size coal having feed ash and sulfur contents of 33.9% and 3.28%, respectively, may produce nearly 28.3 t/h of clean coal with product ash and sulfur contents of 9.15% and 1.61%, respectively.

Jan 1, 2008

By A. Adu-Acheampong

Stope instability at Ashanti Goldfields Company Ltd. (AGC) is a major concern. Using information from field mapping, major discontinuity sets were defined, Rock Quality Designation (RQD) was determined. The stability of wedges in the stope walls was assessed using the commercially available computer program UNWEDGE(Rock Science, 1992). Analytical results indicate that the presence of graphite infilling in joints contributes to instability, while steeply dipping joints control wedge slabbing and wedge toppling in the hanging wall. Stable stope widths and dimensions were determined to range from8.1 to 30 meters (m).

Jan 1, 2003

By Sukru Sumer

East Pit Lake is an artificially created lake that resulted from the remediation and reclamation of surface coal mining operations at TransAlta Utilities' Whitewood Mine in the Wabamun area west of Edmonton, Alberta. The original excavation resulted from the creation of a mine end cut at the northern extent of the mining operation. The area of the surficial drainage basin that feeds East Pit Lake was relatively small. Therefore, most of the inflow and outflow from the lake would result from regional ground water flow. There was a concern about the lake's ability to provide a suitable habitat for a sportfish population. To determine the final recovered water level and rates of recovery, a two-dimensional ground water flow model was used. Data supplied by nested piezometers in and around the mine were used to calibrate the computer simulation and assess predicted recovery.

Jan 1, 1995

By Lane White

The 1989 Annual Meeting and Exhibit of SME in Las Vegas, NV, February 27 - March 2, 1989, was the largest ever, drawing more than 4000 regis¬trants and 240 exhibit booths. Technical sessions included presentation of nearly 500 papers, including symposia on Biotechnology in Minerals and Metals Processing, Surplus Capacity in the International Metals Industry, and APCOM `89 - the 21st International Symposium on Application of Computers and Operations Research in the Mineral Industry. Technical sessions covered the gamut of minerals industry interests; however, the proximity of the meeting to recently surging gold development in Nevada drew special attention to gold operating practices. Several of the papers on gold processing are reviewed below. To keep pace with the strong world- wide interest in gold development, SME has scheduled three additional upcoming programs that will focus specifically on gold: World Gold '89 - Gold Forum on Technology and Practices will be held November 5 - 8, 1989 in Reno, NV, as a joint meeting and exhibit between SME and the Australasian Institute of Mining and Metallurgy. Technical sessions will encompass a full program of papers covering geology and exploration, mining, and mineral and metallurgical processing. Cooperating sponsors for this meeting include the Canadian Mineral Processors Division of CIM, The Institute of Metals, The Institution of Mining and Metallurgy, The Mining, Geological & Metallurgical Institute of India, and The South African Institute of Mining and Metallurgy. Gold '90 - Salt Lake City, UT, February 26 - March 1, 1990, will be a symposium held in conjunction with the 1990 SME Annual Meeting. Current research on the processing of refractory gold ores will generate innovative papers on process mineralogy at this symposium, with special emphasis on gold with pyrite and gold with carbon. Other sessions are planned for gold exploration and mining, gold metallurgy, gold plant design and practice, and gold in scams. Advances in Gold and Silver Processing Conference, October 1 - 3, 1990 will be held in Reno, NV. Preliminary planning calls for technical sessions on heap leaching practice, refractory ore processing, non-traditional lixiviants, bioleaching, metal recovery from solution, and the environmental aspects of processing operations. PLANT DESIGN, OPERATION Technical sessions organized by the Minerals and Metallurgical Processing Division of SME at this year's meeting in Las Vegas covered a wide range of gold operating practices. Eight papers relating to gold plant design, operation, and equipment are summarized here. Preprints of these papers are available by writing to Publications Sales, PO Box 625002, Littleton, CO 80162-5002 ($2.50 per paper for AIME members, $4 for nonmembers). Continuous elution process A. M. Stone, of Bechtel Australia Pty. Ltd., described the "Development of the Continuous Elution Process for Extraction of Gold from Carbon" (pre-print 89-75). Developed by Bechtel Pacific Corp. for Ok Tedi Mining Ltd., the Continuous Elution Process uses the same reagents as batch processes for elution of gold from carbon, while yielding significant savings in stripping vessel size and energy consumed in comparison with equivalent batch processes. The process is also simpler to operate than batch processes. Other advantages include reduced maintenance costs, higher average eluate grade, and near steady final eluate grade. Pilot testing for the Continuous Elution Process was conducted at Western Mining's Kambalda gold plant beginning in December 1982. The Continuous Elution Process is a continuous countercurrent system operating in a pressure vessel at elevated

Jan 1, 1989

By Leonard N. Hill

Cyprus Sierrita Corp. has 16 parallel 5.03 m-diam x 5.8 m long (16.5 ft-diam x 19 ft) primary ball mills, each operating in closed circuit with a nest of cyclones. Before the upgrade to 840 mm (33 in.) cyclones, each mill operated with a nest of five 660 mm (26 in.) cyclones - four in use and one on standby. In this configuration, the mill throughput was 88.5 kt/d (97,500 stpd). Flotation feed averaged 25.9% +212 pm (+65 mesh). The 660 mm (26 in.) cyclones normally operated at an inlet pressure of 34 kPa (5 psi), lower than the inlet pressure of 55 kPa (8 psi) recommended by the manufacturer. The circuit was typically operated with cyclone overflow densities greater than 40% solids to achieve the required throughput. This resulted in inefficient cyclone operation and excessive coarse oversize reporting to flotation. The apexes choked frequently. Larger apexes were tested but reduced the classification efficiency and resulted in circulating loads greater than 800%.

Jan 1, 1994

By John J. Sammarco

Mining has one of the highest annual average fatality rates among major US industries. Health and safety dangers have been inherent to mining since the early days of picks and shovels. Even though miners’ health and safety has improved over the years, mining is still one of the most dangerous occupations. Mining was traditionally a low tech industry. It is now driven by competitive pressures to go high-tech by using programmable electronics (PE) for machine control, atmospheric monitoring and material processing. The industry’s experience with the functional safety of PE is limited compared with other industries. Thus, PE is an emerging technology for mining that can potentially create or worsen hazards.

Jan 1, 1999

By Steve Kral

Worker safety is an issue that transcends industries, whether it be mining, construction, manufacturing or even general office work. In the mining industry, safety and training are particularly important because mining is a dangerous occupation. Throughout the years, federal and state safety regulations have been written and revised to keep up with the changing technologies. And mine operators have installed their own safety and training programs. They have come to realize that a safe and healthy workforce has positive effects on productivity and profitability —not to mention avoiding the high costs of injury-related absenteeism.

Jan 1, 2003

By V. Rajaram

R.C. Rex, Jr. V. Rajaram's paper does not accurately reflect the status of Eastern oil shale development as it stands today. Today, there are numerous firms and research organizations pursuing development of the Eastern oil shale resource. Details of the current projects can be found in the symposium proceedings for the 1985 Eastern Oil Shale Symposium held in Lexington, KY, in November 1985. Additionally, the comparison of the Paraho and HYTORT processes is invalid because the HYTORT process design used it not an accurate representation of the HYTORT process. I will briefly address this point. It is disconcerting to see the author reference hydroretorting work conducted at the Institute of Gas Technology (IGT) (circa 1978) in the introduction, which indicates hydroretorting (the HYTORT process concept) yields of up to 250% of the Fischer Assay oil yield, and then turn around and base the remainder of the paper on the 1981 "Synthetic Fuels From Eastern Oil Shale Report," which depicts the HYTORT process as yielding only 115% of Fischer Assay. Indeed, work conducted at IGT to 1981 indicates commercial oil yields for the HYTORT process would be in the range of 200% to 210% of Fischer Assay. A more thorough literature search by the author would have yielded a 1981 publication by Schora et al., entitled "Update on the HYTORT Process" presented at the Symposium on Synthetic Fuels From Oil Shale in Nashville, TN, October 1981. This paper thoroughly discusses the shortcomings of the referenced study with respect to the HYTORT process. For the interested reader, I can also recommend a June 1984 report entitled "An Economic Comparison of Five Process Concepts for Using Eastern Oil Shale," published by Los Alomos National Laboratory (LA-10106-MS, Parkinson et al., NTIS No. DE84-015981). This study applies a realistic HYTORT design (circa 1982) and indicates that HYTORT is the most econom¬ical method of processing Eastern oil shales (about $20/bbl less than Paraho). Additionally, completion of the HYTORT feasibility study in June 1983 by Phillips Petroleum Co., Bechtel Group Inc., HYCRUDE Corp., and IGT has resulted in development of designs that will make the use of HYTORT on Eastern oil shales even more economic. HYCRUDE Corp., a second-tier subsidiary of IGT, is involved in commercialization and licensing of the HYTORT process and is active in efforts to develop the Eastern oil shale resource. As such, I am disappointed to see outdated material that has the potential for adversely affecting development of Eastern oil shale resources published in MINING ENGINEERING. I can only hope that this response will serve to mitigate any negative opinions that may have been formed. Today, activity in commercializing Eastern oil shales dominates the oil shale scene in the US and indicates a realization of the potential for these shales. Reply by V. Rajaram I appreciate the updates on the HYTORT process provided by R.C. Rex, Jr. I hope that Hycrude's work will lead to the funding of a pilot plant to demonstrate that yields of greater than 200% of Fischer Assay can be achieved in a commercial plant using eastern US oil shales.

Jan 9, 1986